Saving Disconnected Entities with Linq2SQL

I struggled yesterday with saving modified entities back to the database after they were disconnected from their original DataContext. After much googling, I found the way forward is to ensure you have a version column in your database with a timestamp datatype, and map this with a Binary field in your mapping metadata. Then you can call an overload of Attach.

A complete working example below, as simple as I can make it. Hope that helps somebody.

using System.Data.Linq;
using System.Data.Linq.Mapping;
using System.Linq;
using NUnit.Framework;

namespace CustomerSaver
{
    [TestFixture]
    public class Class1
    {
        [Test]
        public void TrySaveCustomer()
        {
            const string connectionString = @"server=.\SqlExpress; database=test;trusted_connection=true";
            Customer customer;

            using(DataContext readContext = new DataContext(connectionString))
            {
                customer = readContext.GetTable().First();
            }

            customer.Name = customer.Name + ".";
            using (DataContext saveContext = new DataContext(connectionString))
            {
                saveContext.GetTable().Attach( customer, true );
                saveContext.SubmitChanges();
            }
        }
    }

    [Table(Name="Customers")]
    public class Customer
    {
        [Column(IsPrimaryKey = true)]
        public int Id { get; set; }

        [Column]
        public string Name { get; set; }

        [Column(IsVersion = true, IsDbGenerated = true)]
        public Binary Version { get; set; } //timestamp column in sql server
    }
}